A. lg. O S11UWS U11C 1CIUU1 VlUlttWl, UVJ VV111V-H CV IdlgC pai L <_>J. LllV^ 

saving effected by compressed air, with or without a power 

Fig. 7. 




Paraffined Board. 

squeezer, is due. Power squeezers are made in various sizes, but 
the smallest size covers by far the largest field. It has been imag- 
ined that by increasing the size of flask and putting in more patterns 
greater production can be obtained, but this is seldom the case, and, 
as previously mentioned, the greatest output comes from medium- 
sized flasks easily handled by one man. 

Fig. 9 illustrates a small power squeezing split pattern machine 
with power draft. Machines of this type can be used with or 



Fig. 8. 




Tabor Vibrator. 



*v 




Conservation Resources 
Lig-Free® Type I 
Ph 8.5, Buffered 



S 236 
L4 
=>py 1 



"1 S 



V* 



.IACHINE MOLDING 



BY 



WILFRED LEWIS, M.E. 



v\ 



From a Lecture delivered at 
THE FRANKLIN INSTITUTE 

PHILADELPHIA 
May 18th, 191! 



Repeated by request at Columbia University, U. S. Naval Academy and read before the 

New England Foundrymen's Association and the Worcester 

Polytechnic Alumni Association 



Copyrighted, 191 1, by The Tabor Mfg. Co. 



COMPLIMENTS OF 

THE TABOR MANUFACTURING COMPANY 

I8TH AND HAMILTON STREETS 
PHILADELPHIA, PA. 



SCI.A305485 



MACHINE MOLDING 

BY 

WILFRED LEWIS, M.E. 

President The Tabor Manufacturing Company 



The art of molding is probably as old as civilization, and it 
may have reached a high state of development before any of the 
events which make up ancient history took place. In fact the 
molders' skill, as exemplified in many antique works of art, has 
been one of the great civilizing forces of the world, and it may 
be questioned whether we can produce to-day any finer examples 
of this art than are to be found among the relics of antiquity. 
But as civilization has progressed the demand for the products 
of the foundry has increased to such an extent as to call for new 
processes, better methods and greater efficiency. The printing 
press, the steam engine, the loom, and, more recently, the internal 
combustion engine, have stimulated the activities of men, aug- 
mented their productive capacities and so enlarged the possibili- 
ties for commercial intercourse that it is difficult to realize how 
few of the comforts of life now enjoyed by the masses were 
within reach of the well-to-do or even the wealthy members of 
society as it was constituted two hundred or even one hundred 
years ago. George Washington, for example, began his career 
as a surveyor ; carried with him the bare necessities of life, often 
slept out of doors on a bed of hay or straw, swam the streams that 
were too deep to ford, and later on, after enduring innumerable 
privations and hardships in many hard-fought campaigns, laid 
the foundation for the government which stands as a monument 
to his sagacity, courage and determination. There were no 
Pullman cars for him and no potentate, however great or wealthy, 
could have traveled a hundred years ago with the luxurious ease 
now within the reach of very moderate means. 

Going back a little further to Columbus, in the height of his 
glory as the first admiral of what was then the greatest power 

1 






in the world, we can imagine his quarters on a flagship which was 
but little if any better in size and comfort than the lifeboat of a 
modern steamer. In short, since man first began to utilize the 
forces of nature, so abundantly provided for his material comfort 
and enjoyment, the productive capacity of the world has increased 
at a rate which staggers the mind to follow and reduces to noth- 
ingness the spells wrought by Aladdin and his wonderful lamp. 

To compare the industrial progress made since the discovery 
of America with all that went before would be a hopeless task, 
but it is not hard to believe that the nineteenth century alone sur- 
passed in the development of the arts and sciences all that was 
inherited from the past and that in all probability the twentieth 
century will do the same. The present rate of industrial progress 
is indeed so rapid as to almost defy pursuit, and it is only possible 
to keep in touch with it in spots where our own special interests 
are involved. 

No man nor set of men can grasp the enormous accumulation 
of knowledge bound up with advancing civilization, and as fast 
as the work of yesterday can be recorded the achievements of to- 
day are almost out of sight. This cannot go on forever at undi- 
minished speed, and it is clearly due to the awakening of man to a 
knowledge of the natural forces within his grasp. It is accom- 
panied at the same time by the destruction of the resources upon 
which it feeds and grows, and it will sooner or later be followed 
by a reaction when posterity begins to descend the slope leading 
back to the ashes from which so much greatness and power has 
been derived, A great deal of permanent value will no doubt re- 
main, but with the prospect of exhausted resources before us, how- 
ever distant that time may be, we may well pause for a moment to 
consider not only the conservation of natural resources, but also the 
efficiency of human labor upon which the conversion of our re- 
sources into wealth depends. We cannot eat our cake and have it, 
but we can make it last a long time and enjoy it with more satis- 
faction if we do not bolt it all at once. 

But the conquest of nature is not to be halted by sentimental 
considerations and the consumption of our resources will no doubt 
go on unabated until their conservation becomes a crying need. 
Its consideration now as a matter of national importance is one of 
the most hopeful signs of the times, and, fortunately for all of us, 
efficiency as well as economy in all the affairs of life is coming 



into the foreground and receiving more attention than it ever has 
before. 

People are beginning to realize that the high cost of living is 
due chiefly to extravagance and waste, and that there is such a 
thing as Scientific Management 1 by which human labor may be 
conserved and its products enormously increased. When rightly 
understood and applied this benefits the wage-earner, the employer 
and the public as well, and goes a long way toward the solution of 
the labor problem which is inseparable from the cost of living. 

Improvements in machinery, combined with power for its oper- 
ation, have worked wonders in the output of labor, but only a frac- 
tion of what can be realized from the same amount of human effort 
when more intelligently directed and controlled. The all-round 
mechanics of former years have well-nigh disappeared and good 
workmen, if obtained at all, must be recruited from such raw mate- 
rial as can be found unemployed. There is always an abundance 
of the inefficient kind, and the problem now confronting the manu- 
facturer is how to make it efficient and valuable. The answer to 
this is to be found in the introduction of an educational system of 
management .not unlike the laboratory system adopted in some of 
our schools and colleges. Men must not be left to their own devices 
to pick up such knowledge as may make them inferior or merely 
good enough workmen. They must be systematically taught to per- 
form the work assigned to them by shop bosses or foremen who are 
interested in the result, and whose chief function it is to teach. In 
this way every shop in the country may become in effect a trade 
school of the most valuable kind, in which the pupils are not only 
taught how to do certain things but how to do them quickly and 
well and earn a substantial reward commensurate with the skill 
attained. No labor-saving machine can produce results without 
human aid in one way or another, and many a machine, good for its 
purpose, has been abandoned to the scrap heap, not from any in- 
herent defect or inability to effect a saving, but simply as the result 
of awkward or inefficient handling. We must have efficient work- 
men as well as efficient machines to obtain the best results, and 
foundries need both as much as, or possibly more than any other 
kind of operating plant to-day. 



1 Formerly known as "The Taylor System." See "Shop Management," Transac- 
tions of A. S. M. E., 1903, and "The Principles of Sceintific Management," Harper & 
Brothers, 1910, by Frederick W. Taylor, M. E. Sc. D. 



Although modern industry depends upon the foundry for a 
large part of its products and the ingenuity of inventors has been 
busily engaged for generations in the evolution of labor-saving 
machinery, very little of this effort has been devoted to the im- 
provement of the foundry itself, and it is only within comparatively 
recent years that machine molding has developed much importance 
as an art. In the year 1800 an English patent was granted for 
molding screws, the patterns for which were backed out of the 
sand by lead screws of the same pitch. This was simply a pattern 
drawing machine of rather ingenious construction, but the English 
records do not touch again upon machine molding until 1839, when 
a very similar patent appears. From this time forward more in- 
terest seems to have been aroused and these patents were soon 
followed by others for packing sand by mechanical means, including 
hydraulic cylinders, stampers and rollers of the road-roller type. 
Machines for molding gears and pipes also' appear in the first half 
of the nineteenth century, and in 1843 we find an American patent 
on the molding of cannon balls. Later, in 1869, the first jarring 
machine patent was taken out, but it is not proposed to give a his- 
tory of the art of machine molding from patent office records, and 
it may simply be noted that the art began in a small way on bench 
work and continued chiefly in its application to small molds that one 
or two men could handle until the end of the last century. Larger 
work was not generally regarded as applicable to machine molding 
until the jarring machine began to emerge from a long period of 
obscurity and demonstrate its peculiar fitness for ramming large 
bodies of sand. Its development for large work belongs mainly to 
the present century and through its means the art of machine mold- 
ing has been extended to embrace nearly everything molded in sand. 
But there are, of course, exceptions and peculiar difficulties which 
will always depend upon the molder's skill for their proper execu- 
tion, with or without the aid of machine, and like any other equip- 
ment the installation of molding machines must depend upon the 
saving to be effected by their use and the outlay needed to effect 
that saving. This leads at once to the consideration of foundry 
costs, the analysis of which should point the way to their reduction. 
These costs are made up of many important elements beyond the 
scope of the subject, and the effect of one item only need be con- 
sidered, that of machine molding, leaving all other items to be 



treated in the same way by those who are interested in attaining 
the highest efficiency in every detail of operation. 

Machine molding began, as has been said, on small work and 
probably one of the best known appliances is the little hand 
squeezer. This is a very simple and effective machine de- 

Small Power Squeezer. 
Fig. 1. 




signed to save part of the time consumed in ramming. Figure 1 
is a little power squeezer adapted to the same class of work as the 
hand squeezer which saved the work of ramming but put upon the 



operator the work of squeezing. There the man still did the work 
but with greater despatch, and therefore more efficiently. Here 
the machine does the squeezing and the operator is less fatigued 
and can work faster. In support of this statement the floor shown 
in Fig. 2 may be offered as evidence. 

Here 270 molds, 12" x 16" x 7" deep, have been put down by 
one man in six hours, and it is stated that this daily performance 
has recently been increased to 315 in the foundry of the American 
Hardware Corporation, where nearly 100 machines of the same 
type can be seen at work. Of course these performances by expert 
operators are not to be expected along the whole line, where the 
average may be in the neighborhood of 200 molds a day, but they 

Fig. 2. 




270 Molds Made By One Man in 6 Hours on Power Squeezer. 

show what is possible, if not always probable, and it remains to be 
seen how a proper day's work on any given pattern can be fairly 
estimated. We are frequently asked to say what our machines will 
do and what production we will guarantee, regardless of the fact 
that we never know anything about the man operating the machine 
and seldom very much about the patterns to be used, the cores to 
be set or the precautions found necessary to insure success in mold- 
ing the same patterns by hand. We know in a general way the 
type of machine required, but until we have actually made molds 



and poured castings, we are at a disadvantage and cannot safely 
guess at results which should be determined from a careful analysis 
of the experience gained in molding by hand. The foundryman 
contemplating the introduction of machines has had the necessary 
experience, but he seldom, if ever, has it in a shape available for 
analysis, and the importance of making observations in detail and 
recording the time required for each and every step taken in the 
production of a mold will be shown. This has been brought out very 
forcibly by Mr. Knoepple in the April number of the Engineering 
Magazine. The suggestions there made are in line with the prac- 
tice of the Tabor Manufacturing Company for the last five or six 
years, but the matter is one that has only begun to receive the at- 
tention it deserves as an important feature of Scientific Manage- 
ment. Consider, for example, a set of patterns mounted in a 
vibrator frame 13 inches by 17 inches for use on a squeezer. See 
Fig. 3. They can be molded either by hand or by power, but if we 
mold them by hand and note down the time taken by every step in 
the process we shall see where to look for a saving and what to 
expect when molded by power. 

Table, I shows the result of observations taken by an experi- 
enced man with a stop watch on molding by hand, and also the same 
observations on the same mold made by machine. The time is 
taken in minutes and hundredths for convenience in summing up. 
Certain operations must be performed whether the mold is made by 
hand or machine, and the table shows the difference in time of the 
two methods. In machine work certain operations are unnecessary, 
as also shown by the table. For instance, item 9 must be done 
more thoroughly and takes more time when the mold is completed 
by hand. Item 11, butt ramming, 0.30 min. is equivalent to squeez- 
ing by power, but it takes five times as long. Item 22 is now done 
by power as a .separate operation. Item 26 to rap pattern takes 
0.48 min. against 0.12 to start vibrator and lift cope at one oper- 
ation on machine. Item 32 patching up, 0.30 min. is not called for 
on machine. Items 33, 34 and 36 are the same in both cases, and in 
molding by power an additional operation (stopping off carriers, 
0.06 min.) is required. In making this mold there are 30 oper- 
ations by hand, footing up 4.20 min., and 27 operations on the ma- 
chine, footing up 2.10 min., which makes the machine time just one- 
half of the time required when molding by hand without the use of 
compressed air. 



Patterns Mounted in Vibrator Frame. 
Fig. 3. 





PATTERNS in frame. 



drag half of mold. 





hard sand match. 



COPE HALF OF MOLD. 



Element Element 

time per time per 

Tart f T piece P iece 

1ABLE 1. hand mac hine 

molding molding 

1 Pick up hard sand match and put on table 0.04 0.04 

2 Pick up pattern and put on hard sand match . . 0.04 0.04 

3 Pick up drag and put in place 0.07 0.07 

4 Shake parting on pattern 0.08 0.08 

5 Pick up riddle and put on flask 0.02 0.02 

6 Fill riddle with sand 0.04 0.04 

7 Riddle sand on pattern 0.08 0.08 

8 Fill drag with sand (3 shovels full) 0.08 0.08 

9 Peen around edge of drag with shovel (butt 

ram hand mold) 0.10 0.05 

10 Put two more shovels full in drag 0.06 

1 1 Butt ram 0.30 

12 Strike off mold (and put bottom-board in place) 0.10 0.07 

13 Pick up bottom-board and place on mold (hand- 

rammed mold) 0.08 

14 Bring yoke over and squeeze 60 lbs. pressure 0.06 

15 Roll mold over 0.08 08 

16 Remove hard sand match (start vibrator on 

machine) 0.07 0.03 

17 Blow sand off mold with bellows (with com- 

pressed air on machine) 0.07 0.05 

18 Repeat operations 6 to 10, inclusive, for cope. . . 0.29 0.29 

19 Fill cope with sand (4 shovels full) 0.10 0.10 

20 Repeat operations 12 to 15, inclusive, for cope. . 0.56 

21 Repeat operations 12, 15 and 17 for cope 0.18 

22 Mark sprue hole (with cope board) 0.05 

23 Remove cope board 0.03 

24 Blow mold off with compressed air 0.05 

25 Cut sprue hole 0.12 0.08 

26 Rap pattern, spike going through sprue hole 

into pattern 0.48 

27 Round sprue 0.10 

28 Remove cope mold (start vibrator on machine) 0.09 0.12 

29 Blow pattern off with bellows 0.09 

30 Blow mold off with compressed air 0.05 

31 Draw pattern from mold (start vibrator on 

machine) 0.45 0.10 

32 Patch up mold (with slick) 0.30 

33 Close mold 0.12 0.12 

34 Remove flask 0.07 0.07 

35 Stop off carrier 0.06 

36 Place mold on floor 0.07 0.06 

Total 4.20 2.10 



10 

It is also apparent from a study of this time-table that the use 
of compressed air alone instead of bellows will effect a saving, and 
that the vibrator in connection with hand molding will also effect a 
greater saving. Making the necessary substitution in the column 
for hand molding in the table for the use of blower and 
vibrator, it will be found that this additional equipment 
alone would reduce the molding time from 4.20 min. to 3.06 min. 
It therefore appears that the blower and vibrator can be used to 
save 1.14 min. per mold and the .squeezer 0.96 min. more. This 
looks as though the blower and vibrator alone saved so much that 
it might not be worth while to put in the machine, but if we look 
again at the increased production, taking hand work as the basis 
for comparison, we see that the output from the use of the former 
is 4.20 -h 3.06 or 1.38, while from the use of the latter it is 
4.20 -f- 2.10 = 2, that is, an increase of only 38 per cent, on hand 
work against 100 per cent, on machine work. 

But it may be argued that another element of time remains 
to be considered, and it must be admitted that no account has yet 
been taken of the time required to distribute a large number of 
molds on the floor. It remains to be shown how far a mold can be 
carried and placed on the floor in .06 min., the time noted, but 
this time .should be taken to about the middle of the space to be 
covered, and perhaps some additional time should be allowed for 
this item, but on the other hand it may be said that no allowance 
has been made for the inexperience of the operator, who was in 
this case a pattern-fitter and not a molder or demonstrator. The 
time given will vary with different men, and it was taken in these 
cases simply for the purpose of illustrating the method by which 
important conclusions can be reached. No better data can be ob- 
tained for fixing prices, and when time is taken by an observer of 
experience who understands his business the stop watch never runs 
unless useful work i,s being done in the right way. A reasonable 
allowance should always be made for contingencies, and a bonus 
put upon the performance of the work specified in the alloted time. 

When patterns are cast in an aluminum match plate, as shown 
in Fig. 4, both cope and drag can be squeezed at the same time, the 
number of operations on the machine is reduced from 27 to 25 and 
the total time from 2.10 to 1.76 min. 



11 



Patterns Cast in Aluminum Match Plate. 
Fig. 4. 




COPE HALF OF MOLD. 



COPE SIDE OF PLATE. 





DRAG HALF OF MOLD. 



DRAG SIDE OF PLATE. 



12 



The snap flasks used are of the usual type, as shown in Fig. 5, 
and in these experiments about 12 inches by 17 inches, 4-inch cope, 
4^ -inch drag. The machine will squeeze molds as large as 14 
inches by 20 inches, but the best production can generally be re- 
alized on smaller sizes. 

Instead of the aluminum match plate, patterns may be mounted 
on a steel plate, as shown in Fig. 6, and when split or flat back this 
is a very convenient method. 

They may also be mounted on a paraffined board held in a 
vibrator frame, as shown in Fig. 7, and when so arranged the mold- 
ing time is substantially the same as for the aluminum match plate 
mounting. 



Fig. 5. 




Snap Flask. 



13 

Patterns Mounted on Steel Plate. 
Fig. 6. 












COPE HALF OF MOLD. 



_iLij 




COPE SIDE OF PLATE. 




SIDE VIEW OF PLATE. 



14 



Fig. 8 shows the Tabor vibrator, to which a large part of the 
saving effected by compressed air, with or without a power 

Fig. 7. 




Paraffined Board. 

squeezer, is due. Power squeezers are made in various sizes, but 
the smallest size covers by far the largest field. It has been imag- 
ined that by increasing the size of flask and putting in more patterns 
greater production can be obtained, but this is seldom the case, and, 
as previously mentioned, the greatest output comes from medium- 
sized flasks easily handled by one man. 

Fig. 9 illustrates a small power squeezing split pattern machine 
with power draft. Machines of this type can be used with or 



Fig. 8. 




Tabor Vibrator. 



15 

without stripping plates and are applicable to a great variety of 
work made in solid or snap flasks. There is less handling time on 
this machine than on the power squeezer, and since each half of 
the mold is made separately the strain on the operator is not so 
great. 

It is also possible to cope off, by means of supporting stools, 

Fig. 9. 




Small Power Squeezing Split-Pattern Machine. 

pockets of hanging sand that would be impracticable on a squeezer. 
It is a very fast machine, but no time study has yet been made to 
show where it gains on the squeezer by reducing the number of 
operations required and the total molding time. There are some 



16 



.-. 




Fig. 10. 



jobs, however, which can be made as quickly on one machine as -on 
the other, and although this is a much higher class of machine than 
the squeezer it does not follow that it is better for every purpose. 
On such machines the cope and drag are frequently made from 
the same set of patterns, and it is therefore a matter of first im- 
portance to have them so located on the pattern plate as to match 
perfectly when the mold is closed. 

Fig. 10 shows a set of pat- 
terns mounted for a split pattern 
moulding machine, the cope and 
drag being moulded from a 
double set of half patterns, the 
impression of the right-hand set 
in the drag matching those of 
the left-hand set in the cope and 
similarly, the left-hand set in the 
drag matching the right-hand 
set in the cope. 

The securing of these two sets of half patterns to the plate 
in a manner to insure accurate matching of cope and drag can 
be best accomplished by the transfer-plate method. 

The first operation in preparing such a set of patterns is to 
make the pattern plate, drilling in it two dowel holes, one of which 
is shown in Fig. 10 at the end of the gate. These holes are drilled 
from a jig supplied with the machine, and their location defines 
the center line of the plate. For the case shown four complete 
patterns are first made, the two halves being doweled together as 
usual before turning. 

They are then numbered and separated, and the halves with- 
out dowel pins are located on 
one side of the pattern plate and 
used as jigs to drill that side of 
the plate as shown in Fig. 11. 
It is necessary to repeat the 
holes thus made on the opposite 
side of the plate and these must 
bear the same relation to the 
center line of the pattern plate. 
To insure this a transfer 
plate of rather more than half Fig. 11. 




17 




the size of the pattern plate is made. Holes to match the center- 
line holes of the pattern plate are drilled in the transfer plate, and 
the transfer and pattern plates 
are placed together ; dowel pins 
are inserted in the center-line 
holes, and the two plates are 
placed under the drill press with 
the pattern plate on top, as 
shown in Fig. 12. In this posi- 
tion the pattern plate is used as 
a jig to repeat its pattern pin 
holes in the transfer plate. The 
transfer plate is then turned over, 
not around on the pattern plate, 

as shown in Fig. 13, the center dowel pins are re-inserted, and 
the transfer plate is used as a jig to drill the holes in the second 
side of the pattern plate, all as shown in Fig. 14. When the trans- 
fer plate is removed, the pattern plate appears as shown in Fig. 
15, and obviously the second set of holes must be truly symmet- 
rical with, the first set and the half patterns when doweled to 
these two sets of holes, due regard being paid to their numbering, 
must also be truly symmetrical and produce perfect joints when 
moulded. 

In the operation of this machine the valve lever on the right, 

shown in Fig. 9, is pressed down 
to squeeze the mold when the 
head is up, and the same lever is 
raised to start the vibrator and 
draw the pattern when the head 
is thrown back after squeezing. 
This lever is also so interlocked 
with the swinging head as to 
prevent movement in the wrong 
direction at any time. Small 
split-pattern machines are also 
made with hand draft, and by 
some operators hand draft is 
preferred to power, but it is applicable only to small machines 
and mechanically the construction of the power draft is superior. 
Split-pattern machines have been on the market for many 




Fig. 13. 



18 



years and their value is recognized and appreciated, but unfortu- 
nately they have to be built for a flask of fixed dimensions of at 

least fixed in length or width to 
fit the flask pins on the machine. 
They are expensive to build, 
rather inflexible in their appli- 
cation, and within the last few 
years they have been superseded 
very largely by roll-over ma- 
chines with straight pattern 
draft to ram by hand or by 
power. An ingenious hand-ram- 
ming roll-over machine, with 
mechanism for rapping the 
pattern carrier and dropping the flask from the pattern, was 
brought out by Teetor in 1889, in which plated patterns are 




Fig. 14. 




Fig. 15. 



carried in a roll-over frame to which the flask is clamped and 
rammed in the usual way by hand. When rolled over, a sup- 
port beneath is brought up by a hand lever, the flask is undamped 
and the pattern rapped by turning a hand wheel on the trunnion 



19 



shaft. At the same time the pattern is drawn by lowering the 
flask. A few of these machines can still be found in use, but 



Fig. 16. 




Tabor Roll-Over Machine With Hand Draft. 



the rapping mechanism is not durable, the machine is rather lim- 
ited in its scope and other types have displaced it for some time. 

The French machine of Bonvillan & Ronceray is a modifica- 
tion of this type, in which the outer trunnion is omitted and power 



20 

is added for squeezing the mold and drawing the pattern. This 
will be remembered as having been exhibited at the Foundry Con- 
vention held in Philadelphia in 1907. It has a number of attractive 

Fig. 17. 




Power Roll-Over Machine With Power Draft. 



features and is said to be very successful in France, where hy- 
draulic power is more popular than it is here, but the machine has 
not been so successful on this side of the Atlantic, for the simple 
reason, no doubt, that water cannot compete with air as a working 
fluid for foundry use. 



21 

The advantage of rolling over to draw a pattern is well known 
and in some cases it is an absolute necessity. This has led to the 
development of a large number of roll-over machines, nearly all 
of which drop the mold away from the pattern after the manner 
of Teetor, but there is one exception, as shown in Fig. 16, and this 
lifts the pattern from the mold in what is generally admitted to be 
the logical way. Logical because the pattern is generally lighter 
than the mold and preferably the part to be manipulated. The 
machine illustrated is shown as fitted with a grate-bar pattern hav- 
ing 140 deep pockets, into which the sand is thrown by hand or 
settled by jarring the swing frame against its stops before ram- 
ming in the usual way by hand. Throwing the sand by hand is 
preferred, because the jarring process is not uniform and naturally 
varies with the distance of different parts of the pattern from 
the turning center. 

The flask used in this case is 14 inches by 37 inches by 5 inches 
deep, and the time required for a complete cycle of operations was 
5.81 min. The cope for this grate bar is almost flat and requires 
no machine. It could be made by a helper who would have enough 
spare time to assist in rolling over, and probably eight to ten molds 
an hour could be made by experienced men. 

In this machine, which takes a flask .24 inches wide and has 
7-inch pattern draft, the swing frame and sliding head are coun- 
terbalanced by helical springs. These can be adjusted to the 
weights to be carried and the pattern is drawn by a hand lever at 
one side. 

Since the weight that can be conveniently rolled over by hand 
is limited to three or four hundred pounds, heavier molds naturally 
require power, and in Fig. 17 we have a machine which rolls over 
and draws the pattern by means of a cylinder and plunger, using 
compressed air on hydraulic oil or water to effect the movements. 

The illustraton shows the pattern drawn and rolling back into 
position for another flask. In these machines a vibrator is attached 
to the swing frame and this materially assists in making a perfect 
draw, the main object of these roll-over machines. They are de- 
signed to save pattern drawing and finishing time, and where 
patterns are of such a character that the margin for this saving is 
small the time study will show it and possibly suggest a jarring 
machine instead. But molding machines do much more than save 



22 

time in molding and are often worth all they cost in the saving of 
patterns, the saving in metal and the saving in machine work by 
reason of the greater uniformity and closer finish of the castings 
produced. 

An important feature of these machines is the levelling cradle, 
of which a number of types have been developed to set the flask 
with reference to the pattern board regardless of irregularities in 
the bottom board upon which it rests. 

Such machines may be fitted with long patterns overhanging 
the swing frame for a considerable distance at each end. This 
possibility indicates the scope of the machine and the advantage 
of rolling over about an axis parallel to the length of the flask 
instead of about a normal axis as is done on machines of the 
French type. 

Time study on large work may show that a material saving 
is effected in finishing, in ramming or in both, and where ram- 
ming time is the principal item a jarring machine is the equip- 
ment most needed to reduce costs. There are quite a number of 
jarring machines on the market, all of them covered by the original 
claim of Hainsworth in his patent of 1869, which is so refreshing 
for its simplicity and breadth that it is worth quoting: 

"The packing of sand, for a mold, in a flask, by raising the 
same, together with the pattern, and letting them all drop upon a 
hard bed, substantially as shown and described." 

There were no permutations and combinations of elements 
making an extended series of claims calculated to exhaust the 
patience of the reader. All he wanted was the whole field, and 
he secured it in a single claim, but it is not certain that the packing 
of sand in this way was altogether original with Hainsworth, and 
there is ample ground to suspect that groceries of all kinds have 
been packed in paper bags by the same jolting process before the 
memory of man runs otherwise, and some of these (dried currants, 
for instance) there is reason to believe have alwavs contained a 
liberal admixture of sand. The packing of sand by jarring is 
therefore in all probability as old as the hills, but since the broad 
claim of Hainsworth no longer troubles us we must look among 
later improvements within the field that he covered for the de- 
velopment of the art. This patent seems to have attracted very 
little attention when it appeared and no further inventions along 



23 

this line are on record until 1878, when Jarvis Adams gave some 
impetus to the art and later followed it by a number of patents. 
The Adams machines were, however, rather crude and very little 
progress in the art was really made until compressed air came into 
general use as a medium for the transmission of power. 

At the present time nearly all jarring machine builders con- 
template the use of compressed air, whereas originally, and until 
about the beginning of the present century, they were operated 
mainly by hand or by cams on a power shaft. The development 
of the jarring machine is an interesting study, but no attempt will 
be made to follow it through all its ramifications ; a few examples 
only representing the last ten years will be considered. In the 
Tabor machine first built the jarring table was struck underneath 
by a heavy plunger actuated by compressed air. The blow raised 
the table a short distance from its support, upon which it fell back, 
striking a second blow. Some of these machines are stilll in 
use, but it cannot be said that they are very efficient or successful, 
and they were superseded five or six years ago by the Tabor jar- 
ring machine now in common use, as shown in Fig. 18. 

This is a plain machine with the jarring cylinder formed 
in the table mounted upon an upstanding plunger. By this con- 
struction the table is given enormous strength and stiffness and 
the. central bloiu of impact is distributed equally in all directions. 
The plunger is part of a heavy piece of cast iron forming the 
anvil, which in turn rests upon a large mass of concrete. Origi- 
nally the main valve was operated directly by tappets attached to 
the table adjustable for any desired length of stroke, and later 
it was modified to operate through the medium of a pilot valve. 
To avoid unnecessary intensity in the blow struck by the table 
upon its anvil a few layers of leather or other non-resilient mate- 
rial are introduced as a cushion. These reduce the wear and tear 
and noise, without having any material effect upon the action of the 
machine on sand. 

The plunger base rests upon concrete to form an anvil, 
and as to the mass of concrete, it may be said from the operating 
standpoint the more the better, but this must be limited, of course, 
with regard to the cost and the natural bed beneath. In a general 
way, about two cubic feet of concrete for every square inch of 
area in the jarring cylinder is recommended, but if there is a 



24 

rock bottom beneath, the use of very little concrete is advisable, 
or just enough to level up under the cast-iron plunger base. Some 
builders recommend more concrete than this, some less, and in addi- 
tion to the concrete a heavy wooden cribwork is frequently put 
in beneath to prevent the transmission of the shock of impact 
into the ground. This is in accordance with the usual practice 



Fig. 18. 




Plain Jarring Machine. 



under steam-hammer anvils, and it may have some beneficial effect 
but it does not eliminate the whole trouble and the wooden crib 
is scarcely worth its additional cost. It is not generally safe to 
set up finished molds with hanging sand in the neighborhood of 
a jarring machine of this type and in some foundries the jarring 
machine has been put out of service for days or weeks pending 
the completion of large floor work. In fact, the damaging effect 



25 

of large jarring machines is too well known to need confirmation, 
and to reduce this to a minimum, the drop of the table has been 
decreased while the foundation has been increased. 

But there is a limit to the relief afforded by reducing the drop, 
because upon this the ramming effect primarily depends. The 
shorter the stroke the less the ultimate density attained and the 
less the efficiency of the machine. This can be demonstrated in a 
practical way by ramming up a deep mold on short strokes until 
the sand ceases to pack any further. Increasing the length of stroke 
very considerably alters the effect of the next blow. The sand will 
pack further immediately and the conclusion in favor of the long 
stroke as more efficient in packing sand is inevitable. 

With the object of eliminating ground ,shock and yet retaining 
the use of any stroke desired the Shockless Jarring Machine, Fig. 19, 
has been desinged. It requires no foundation other than a base to 
sustain the static load upon it, and it is more efficient in operation 
than a plain machine mounted on a •wooden crib whose anvil tveighs 
twice as much. The principle upon which it operates will be under- 
stood from the sectional elevation shown in Fig. 20. The plunger 
base forming the anvil is mounted for convenience in an anvil cyl- 
inder and rests upon a number of long compression springs. When 
air is admitted to the jarring cylinder the entire weight of the anvil, 
table, and load is carried upon these springs and they are therefore 
compressed and in readiness to expand when the air is exhausted 
and the table falls. At the beginning of this movement the loaded 
table is impelled downward by the same force that moves the anvil 
upward, and although some of the force of the springs is exhausted 
as the anvil rises, the loaded table and the anvil acquire substan- 
tially equal momenta which neutralize each other when impact takes 
place. To compensate in a measure for the loss of spring pressure 
as the anvil rises, the exhaust from the jarring cylinder may be 
carried into the anvil chamber before being discharged. This is 
accomplished by a combination valve, consisting of a large main 
valve of the steam-hammer type in connection with a small pop 
valve such as is used on small power squeezers and split-pattern 
machines. These valves are attached to the anvil or plunger base 
and the pop valve is opened and closed by tappets on the jarring 
table. When the table drops the pop valve opens, admitting pres- 
sure beneath the main valve, which rises and puts the jarring 
cylinder in communication with the air supply, at the same time 



26 
Fig. 19. 




Tabor Shockless Jarring Machine. 



27 
Fig. 20. 




Section of Shockless Jarring Machine. 



28 

opening the anvil cylinder to exhaust. When the limit of stroke is 
reached the pilot valve opens to exhaust and the main valve opens 
to drop the table. The air from the jarring cylinder rushes into 
the anvil cylinder, expanding to much lower pressure, which is 
nevertheless very effective in the large anvil cylinder and causes 
the loaded table and anvil to collide with greater force and effect 
upon the sand. The supply of air to these valves is controlled by 
an air cock at the operating stand and the table runs automatically 
as long as the air is turned on. At the same time the stroke of the 
table is controlled by another lever, adjustable, if desired, while the 
machine is running. The purpose of the pilot valve is to provide 
a controlling means, easily manipulated, that will give the delayed 
action required by the main valve. This always presents full open- 
ings during the table movement up or down, and the ample lap 
on the ports gives time for expansion in the jarring cylinder under 
light or medium loads after the air supply has been cut off. Of 
course, under full load, or thereabout, there can be no appreciable 
expansion in the jarring cylinder. 

Fig. 19 is taken from a photograph of a 13-inch shockless ma- 
chine with 4-foot by 6-foot table. A machine of this type will ram 
any mold, large or ,small, in a minute or less time, and the saving to 
be effected by its use on large work is practically the whole of 
the ramming time by hand. It will not ram small work, such as 
that on which time study was first given, as quickly as a squeezer 
or split-pattern machine, and such a jarring machine for half molds 
weighing less than 1000 pounds is not often recommended, but 
for large deep work particularly it is by far the best machine for 
packing sand. It is not, however, every pattern that can be rammed 
in this way, and care must always be taken to avoid projections on 
the pattern which interfere with the proper flow of sand. This 
sometimes necessitates the use of a core not required for hand ram- 
ming, but the patterns when mounted for jarring require fewer 
repairs and the cost of adaptation to the jarring process is soon 
recovered. Although the jarring machine is not universal in its 
application, it covers a very broad field of work, and by this method 
of ramming the sand is packed as it should be, densest at the sur- 
face of the pattern and of decreasing density above, thus favoring 
the escape of gases when the mold is poured. 

The packing of sand by jarring is naturally greater in a vertical 
direction than horizontally, but this difference varies with different 



29 

sands, some of which are much more plastic than others. Sand 
for steel castings is especially so, and this will pack around patterns 
that could not be used for cast-iron. Other sands have so little 
bond in their composition as to pack only under very hard ramming 
with a large excess of sand or a heavy weight on top, and to obtain 
the best results a good deal of judgment and patience is frequently 
required. This has led to the provision for a variable drop under 
easy control, as shown in Figs. 18, 19 and 20. Here an adjustable 
stop on a bell crank lever or rock shaft, carried by the jarring table,, 
is made to engage the pilot valve lever, and the position of this 
stop is controlled by a latched lever on the operating stand. By 
this means the stroke can be varied while the machine is running, 
and good practice sometimes requires a short stroke followed by 
longer ones as the sand settles into the flask. A long stroke at first 
when the mold is deep sometimes causes the entrained air to force 
a passage to the surface and cut a channel in the sand, and this 
can be avoided by a few short strokes to settle the sand in the deep 
pockets before ramming as hard as desired to compact the mold. 
The back and sides of a mold are not, of course, rammed as hard 
as the bottom, and to increase the density in these parts the sand 
may be heaped up on the back of the mold, or a sand frame can 
be used in which a definite depth of excess sand is carried. It 
frequently happens, however, that the labor of handling a large 
amount of excess sand is greater than that of butt ramming the 
back of a mold by hand after the jarring has been completed. 
It is also practicable to follow the jarring by squeezing, and for 
this purpose the little squeezer shown in Fig. 1 is arranged to jar 
as well as to squeeze. When so arranged, however, the base is 
made much heavier to act as an anvil, and means may be provided 
to jar automatically. Machines of this type are applicable espe- 
cially to deep work, and care must be taken not to squeeze too 
hard. This pressure is measured by a gauge attached to the squeez- 
ing cylinder, and the proper combination of blows and pressure 
can be determined by experiment in any given case. 

When deep molds are packed by squeezing only they are much 
harder on the back next to the squeezing head than they are at the 
pattern surface. This is due to friction between the sand, flask and 
pattern, which resists the flow and produces just the opposite effect 
from jarring. In fact, the difference in density is so great as to 
suggest the advantage of packing the sand from the bottom up 



30 

instead of from the top down, and before jarring machines came 
into general use, bottom ramming machines, in which the patterns 
were pushed up into the sand, were recognized as ideal in principle, 
and they were used with more or less success. But the method 
is open to the objection that it necessitates a predetermined quantity 
of sand reduced in bulk by a definite amount of compression, and 
these conditions upon which success depends are not always real- 
ized in practice. The amount of sand contained in a given space 
will vary with its temper and the manner in which it is handled, 
and unless these conditions are invariable the sand will not be uni- 
formly packed by bottom ramming, and jar ramming is seen to 
have advantages not possessed by any other method 

In jar ramming nothing, of course, can be more efficient than 
an anvil bedded on rock and therefore of practically infinite weight, 
but even a rock bottom does not prevent the transmission of ground 
waves, and when a wooden crib is used to cushion the blow the anvil 
yields to the impact and softens the effect. The advantage of the 
uprising anvil will therefore be demonstrated and its action illus- 
trated by reference to two cars on a horizontal track. Let these 
cars be of equal mass or weight and let them be separated a given 
distance. Now block the wheels of one car and draw the other to 
it by a uniform force. Assuming the impact to be inelastic the 
two cars will move on together at half the velocity acquired by 
the moving car at the time of impact. The shock of collision is the 
same on both cars; one gains what the other loses, one-half of the 
velocity of impact, and the square of that change in velocity repre- 
sents the ramming effect. If the stationary car had been of infinite 
mass the moving car would have lost all of its velocity and suffered 
four times the ramming effect. 

Or, we may say, to invert the comparison, when one car 
strikes another of the same weight the ramming effect is one- 
quarter of what it would be if the car ran into a stone wall, or 
encountered a mass so much superior as to have substantially the 
effect of infinite mass in checking its velocity. Now, if both 
cars are free to move and are drawn together by the same force 
as in the first instance, the same amount of kinetic energy will 
be developed, but it will be divided between the two cars and totally 
absorbed by inelastic impact, each car sustaining one-half the 
shock instead of one-quarter. Therefore, when both cars move 
together the shock of impact is twice as great as when one car 



31 



waits to receive a blow from the other one. Furthermore, the 
highest efficiency, or the greatest shock, is realized between any 

Fig. 21. 




Combined Power Roll-Over and Plain Jarring Machine. 

given pair of cars for any given amount of work done when both 
cars are actuated by the same force and acquire equal momenta 
in equal times. This is true for cars of unequal weight as well 



32 



Fjg. 22. 




Combined Power Roll-Over and Shockless Jarring Machine. 



33 

as for the cars of equal weight just considered, and it can be 
shown when one car is made heavier than the other to act as an 
anvil that when both cars are free to move the shock on the lighter 
car is greater than it would be against a car of double the weight 
standing to receive the blow. It is not claimed that the shockless 
jarring ■ machine is always twice as efficient as a plain machine 
having the same weight of anvil mounted on a wooden crib, 
although it is sometimes more than twice as efficient. It is simply 
maintained that the shockless jarring machine is more efficient than 
a plain machine having an anvil twice as heavy mounted on a 
zvooden crib. But the efficiency of a jarring machine does not 
depend altogether upon the weight of its anvil ; solidity of con- 
struction contributes something and the length of stroke still more. 

Instances could be cited where production has been increased 
five times by the installation of a jarring machine and still greater 
gains have been made from machines which combine the jarring 
and pattern drawing features just described. 

Fig. 21 shows such a power roll-over machine in combination 
with a plain jarring machine, and Fig. 22 shows a power roll-over 
machine in combination with a shockless jarring machine. 

Fig. 23 shows a grinder frame mold made on the plain com- 
bination machine. This half mold was made by two men in ten 
minutes and a complete mold, including core setting, could be 
made in half an hour. 

Originally two men made two molds a day by hand. With 
the aid of a jarring machine they made five a day, and it appears 
from the time taken for a half mold on a combination machine that 
twenty a day might be expected. This machine was built however 
for another purpose and the grinder frame pattern was simply used 
to demonstrate the capacity of the machine. 

Fig. 24 illustrates another combination of pattern drawing and 
jarring machine in which the pattern drawing cylinders are mounted 
on the anvil base and coupled by a squaring shaft to work in 
unison. The power used is compressed air and this acts upon 
liquid within the pattern drawing plungers to lift a flask from its 
pattern through a stripping plate or to lift out a pattern after the 
flask has been rolled over. 

This is a convenient machine for miscellaneous work, but 
where a large number of molds are required from the same pattern 
the machines shown in Fi^s. 21 and 22 are more efficient. 



34 
Fig. 23 






■a 








Half Mold 45" x 60" x 18" Weighing 4,000 Lbs. Made on 

COMBINED M.ACHTNE. 



35 



Fig. 25 illustrates a Portable Shockless Jarring Machine to 
ram half molds weighing about 1,000 lbs. and weighing itself 
about 2,000 lbs. It is mounted on broad-faced wheels to run on 
planks laid in the foundry floor and the anvil is carried on spring 

Fig. 24. 




Combined Jarring and Stripping Machine. 



trucks arranged to absorb shocks and vibrations. It will be seen 
that similar trucks extended to displace the wheels and take a 
permanent bearing on foundations may be used under the machine 
shown in Fig. 24 to convert it into a shockless combination machine. 
In shockless machines of this type, however, no advantage can 



36 



be taken of the energy remaining in the compressed air when 
exhausted from the jarring cylinder, and the anvil is boosted to 
meet the falling table by the action of its supporting springs only. 
The machines shown in Figs. 21 and 22 which jar ram roll-over 
and draw the pattern by power may be combined with a squeezer as 



Fig. 25. 




Portable Shockless Jarring Machine. 



shown in Fig. 26 to jar ram squeeze roll over and draw the pat- 
tern by power, and the same machine on shallow work may simply 
be used to squeeze roll over and draw the pattern by power. 

Jar ramming in combination with other methods of molding 
therefore opens up a broad field which promises to bring the art 
of molding more completely under the domination of machines. 



37 



Fig. 27 represents a mammoth jarring machine of the shockless 
type recently completed for ramming half-molds up to 25 tons in 



Fig. 26. 




Jarring Squeezing Roll-Over Machine. 



weight. The table is of cast steel, 8' x 12' on top and this is 
mounted on a plunger 3' in diameter with an enlarged base 5" in 
diameter weighing about 65,000 lbs. The whole machine weighs 



38 



between 90,000 and 100,000 lbs., including about 3,000 lbs. of steel 
springs which support the plunger. It is believed to be the largest 

Fig. 27. 




36" Tabor Shockless Jarring Machine with Table 8' x 12'. 



jarring machine of any type yet built and while running no shock 
whatever can be felt in the floor on which it stands. Another 



39 

advantage to be considered from the use of shockless machines 
is their permanence of position when once leveled up and set 
with concrete. A common complaint from the use of plain jarr- 
ing- machines is made on account of change of alignment from 
constant hammering on a settling foundation and the heavier the 
weight to be handled the greater the advantage of the shockless 
machine. 

Although the foregoing is not a complete summary of the 
art of machine molding and many types of machines have neces- 
sarily been omitted, the point to which particular attention is in- 
vited is the harvest awaiting the introduction of Scientific Man- 
agement in the foundry and its bearing upon the proper selection 
and use of molding- machines. 




JAN 30 1912 



Compiled 

and 

Engraved 

by 

the Peters Co. 

Pliiladelphia 



One copy del. to Cat. Div. 



JAN 30 1912 



LIBRARY OF CONGRESS 




003 318 366 



